Dear Brian,
Could you tell me specific voltage gradient spec. for each kinds of PWB:
handheld, consumer, mother board ...?
Which document may I refer ? (IPC, MIL ...)
Best regards,
Tri'.
----- Original Message -----
From: Brian Ellis <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 22, 2000 6:08 PM
Subject: Re: [TN] Electrical testing of bare board
> Howard
>
> I presume by 3,5 mil, you mean 0,0035", equivalent to about 80
micrometres. Putting 250
> V across this, with or without mask, gives a voltage gradient of about
3000 V/mm which
> is HORRENDOUS. A typical acceptable voltage gradient without mask is about
100-150
> V/mm, maybe double that with mask, if all the best conditions are united.
If your
> substrate has absorbed any humidity (and it is likely that it will have
done), you will
> be pulling apart any ionics in the material. At the best, you will damage
it. At the
> worst, it will simulate an arc welder. Please don't do it.
>
> Brian
>
> Howard Lin wrote:
>
> > Hi TechNetters,
> >
> > We do some testing of bare board right now. Can anyone point out what
> > different between board with solder mask and without solder mask on
> > electrical testing process? If we apply 250 voltage on 3.5 mil spacing
> > pattern , will it damage electrical character? Is there copper migration
> > occuring during 250 voltage testing?
> >
> > Howard Lin
> >
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